Amazon.com : K&F Concept 58mm Magnetic MCUV CPL Fixed ND1000 Magnetic Basic Ring 4-in-1 Lens Filters Kit with 28 Multi-Coatings for Camera Lens (Nano-X Series) : Electronics
PALL Magnetic Filter Funnel, 47 mm
Magnetic filtering & separation | Goudsmit Magnetics
K&f Concept Nano X Series 49-82mm Magnetic Lens Filter Kit Gnd8+nd8+nd64+nd1000+magnetic Adapter Ring 5 In 1 Quick Swap System - Camera Filters - AliExpress
Magnetic Boiler Filter | System Efficiency | NIBCO
Magnetic filters for pressure lines | Goudsmit Magnetics